The field of this invention relates to a liquid gauging device and more specifically to a liquid gauging device to be employed in conjunction with a predetermined liquid level within a measured container.
The subject matter of this invention is designed in particular to be employed upon large volume containers, such as a gasoline tank truck, or the like. However, it is considered to be within the scope of this invention that this invention could be employed in other fields, such as upon smaller sized containers and not only gasoline type of containers but also any type of liquid containing container.
A gasoline or fuel oil tank truck is a very precisely measured container. At the present time, each tank truck includes a volume calibration system which normally takes the form of a threaded rod extending from the top of the tank truck into the container and upon the threaded rod are located one or more threadable wafers. A calibrating body, usually in the form of Government officials, place a desired amount of liquid within the container (usually between fifteen hundred and twenty-one hundred gallons), and then manually threads the wafer until it contacts the top surface of the liquid. At times there may be two or more wafers established at different points along the threaded rod to establish different gallonages. This wafer or wafers are then fixed and sealed in their established position. If anyone alters the position of the wafers, it is readily apparent by the breaking of the seal.
Anyone ordering product to be transported by the tank truck has the right to inspect these wafers to insure that the person is receiving their number of gallons which that person has ordered. This requires a person to physically climb on top of the tank truck and open the hatch into the tank truck to observe the position of the wafer with respect to the fuel. At the time of opening the hatch, a substantial volume of gas fumes escape into the atmosphere. The amount of gas from a single tank truck escaping into the atmosphere is not a significant amount, but when taken in view of the fact that there are approximately over one hundred and forty thousand tank trucks in the United States at the present time and with every one of these tank trucks having their hatches opened each day a significant amount of gaseous fumes are expelled daily into the atmosphere. The releasing of fumes to the atmosphere is in violation of the Governmental Environmental Protection Agency and the Air Pollution Control Department. The breathing of such gaseous fumes is not particularly desirable from a health standpoint. Also, each time the gaseous fumes are exposed to air there is always the potential danger of fire and such fires have occurred while the tank trucks have been filled within bulk plants.
At the present time, there is a new type of system that is being installed within tank trucks which requires the tank trucks to be filled from the bottom and the hatch covers on the top of the tank truck to be permanently closed. However, there still presents the problem of permitting, in some way, the person receiving the product to know that he is obtaining the purchased amount of product. Therefore, some gauging system must be incorporated into the tank truck which is capable of gauging the quantity of fuel within the tank truck and displaying this amount exteriorly of the tank without requiring the opening of any hatch cover into the tank truck.
In the past, there have been known systems in order to achieve the previously mentioned end result. These past systems have been structured to include some type of float which is movable with respect to the surface of the liquid contained within the tank. However, such floats are movably by mechanical means and it is very common that such floats will stick thereby giving inaccurate readings.
There is a definite need for a device which will be capable of denoting whether a certain quantity of liquid is contained within a tank and also for the measuring instrument to be safe in a hazardous area, maintenance free and a hundred percent reliable over an extended period of time.